Where ever it says "how many narcotics needed" on this app is a lie. You almost always need way more than is recommended on here. So do not plan your tames around how many narcotics this app recommends for it.
The method I used to tame was picking up the beaver with my crystal wyvern and dropping it in a taming pen. Pretty easy knockouts but their torpor drop rate is INSANITY and you can't leave then for more than 3 minutes. Feed them either mejoberries or crops (kibble is really expensive but if you want to do that, go for it).